Linear motor systems are well known to the art and have been found to be advantageous for use in robotic systems for use in "pick and place" applications wherein it is desired to locate components upon a substrate with high accuracy. One typical system is shown, for example, in U.S. Pat. No. 4,823,062, issued Apr. 18, 1989 and assigned to the assignee of the present invention.
In one typical embodiment, the robot is mounted upon a linear motor of the two-dimensional type which is movable in two mutually perpendicular directions along a platen. The robot may typically pick up a component from a feeder bin, precisely position the component above a substrate and deposit the component at said position.
Many robotic applications require greater and greater forces dictated by the specific application. The conventional approach to achieve the desired power capability is to produce a linear motor of increasing power and hence of increasing size. This approach has the disadvantage of providing a linear motor having a significantly increased surface area which confronts and interacts with the cooperating surface of the system platen to develop the desired forces to propel the linear motor along the surface of the platen. The increased surface area of the linear motor renders the linear motor more susceptible to deviations between surface areas of the linear motor and the platen due to platen warpage which typically results from limitations in the manufacturing process, the exorbitant costs of producing a platen having near-perfect planarity, temperature changes, and the like, resulting in a loss of power, as well as erratic operating behavior in the linear motor due to the spacing deviations between the interactive surfaces of the linear motor and the platen. Increasing the size of the linear motor also increases the difficulty and cost of producing a planar confronting surface of the linear motor which interacts with the platen further reducing driving power and/or consistency of driving power.